Users of portable devices desire optical devices that are compact, exhibit high resolution, and have a variety of photographing functions. For example, the photographing functions may include an optical zoom-in/zoom-out function, an auto-focusing (AF) function, a handshaking absorbing function, or an optical image stabilization (OIS) function.
In order to realize the various photographing functions described above, the conventional method has been to combine several lenses and directly move the combined lenses. However, the size of an optical device may increase when the number of lenses is increased as described above.
Auto-focusing and handshaking absorbing functions are implemented by moving or tilting several lenses, which are fixed to a lens holder and aligned with the optical axis, along the optical axis, or in a direction perpendicular to the optical axis. To this end, a separate lens-driving device is required to drive a lens assembly, which is configured with a plurality of lenses. However, the lens-driving device exhibits high power consumption, and a glass cover needs to be separately added to a camera module in order to protect the lens-driving device, thus causing an increase in the overall size of a conventional camera module. Therefore, to solve this, studies have been conducted on a liquid lens unit, which performs auto-focusing and handshaking absorbing functions by electrically adjusting the curvature of an interface of two types of liquids.